This invention relates generally to the field of instrument panels. In particular, this invention relates to a thin-lit panel construction designed for providing general illumination for the instrument panel of an automobile.
In today""s motor vehicles, it is necessary to provide a well-lit instrument cluster such that the operator can quickly scan the requisite gauges and view the information needed without taking his or her eyes off of the road for an extended period of time. The light source must be clear and bright, yet not bright enough to affect the night vision of the operator. It must also provide a uniform level of light to the instrument panel. It is also desirable to have an instrument panel that is as thin as possible in order to save space in the design of the dashboard of the vehicle.
In the past, large, incandescent light sources were used to provide light to the instrument panel These light sources were placed directly behind the gauges that needed illumination. However, these large light sources caused the package size of the instrument panel to be quite bulky and large. Furthermore, the sources also consumed much power and gave off an undesirable amount of heat. Moreover, the sources had relatively short life spans and required frequent replacement due to burnout. In order to reduce the thickness of the panel, designers began to use light emitting diodes (LEDs) that are much smaller, use less power, have much longer lifetimes and give off less heat. However, LEDs produce light in very localized areas, and it became necessary to diffuse the light in order to produce useful illumination for a relatively large area such as an instrument panel.
U.S. Pat. No. 5,695,269 proposes the use of LEDs aligned on the edge of a light pipe to backlight an instrument panel. The light from the LEDs is transmitted into a light pipe upon which a sheet of prismatic material having defined grooves is mounted. These grooves must be precisely measured and formed in order to redirect the light from the LEDs out through the instrument panel. This produces a well-lit instrument panel without giving off too much heat or using too much power. This design also allows the use of different colored LEDs to provide different colors of light to certain sections of the instrument panel. However, a disadvantage of this device is that the prismatic material must be adhered to the light pipe, adding to the thickness of the package. Additionally, the cost of producing such an instrument panel is increased because of the extra design and machining costs of the prismatic material and its grooves due to their complexity.
U.S. Pat. No. 6,036,328 discloses a plane-shaped lighting device with a high light-incidence efficiency as well as a very thin profile. This device places a light source at the edge of a light-directing plate. The light from the light source is transmitted through the light-directing plate and reflected off of a light-reflecting plate adhered to one surface of the light-directing plate. The light-reflecting plate redirects the light out of the light-directing plate and illuminates the instrument panel. The disclosed embodiment of this device uses an array of LEDs placed at the edge of the plate. Because the LEDs are placed at the edge of the plate, the designer must account for this extra space on the thin sides of the instrument panel. This can lead to design difficulties. The fact that the light-reflecting plate extends across the entire light-directing plate necessitates the array of LEDs due to diffusion of the light. Since there is a large reflective area, more light is needed to provide enough illumination. The extra layer added by the light-reflecting plate also adds to the thickness of the package. It is desirable to even further increase the light efficiency as well as decrease the thickness of the package.
In one embodiment a thin panel lit cluster includes a graphics appliquxc3xa9 with a first and second side and at least one opaque section and one translucent section. A light-carrying panel with a first and second side is positioned such that the first side is adjacent to the second side of the graphics appliquxc3xa9. The light-carrying panel has at least one opening defined in it and at least one light source is positioned to align with the opening. Opposite the light source, the light-carrying panel has a first light-redirecting area nearest its first side. In another position on the light-carrying panel, there is a second light-redirecting area nearest the second side of the light-carrying panel and opposite a translucent section of the graphics appliquxc3xa9.
In another embodiment, a thin panel lit cluster includes a graphics appliquxc3xa9 with a first side and a second side and at least one opaque section and at least one translucent section. A light-carrying panel with a first side and a second side is positioned such that the first side is adjacent to the second side of the graphics appliquxc3xa9. The light-carrying panel has at least one opening defined in it and at least one light source is positioned to align with the opening. Opposite the light source, the light-carrying panel has a first light-redirecting area nearest its first side. In another position on the light-carrying panel is an area of light-absorbing material positioned such that light is transmitted through the light-absorbing material and out thorough the translucent sections of the graphics appliquxc3xa9.
In another embodiment, a method for providing general illumination to an instrument panel is provided. The method includes the steps of providing a light-carrying panel with a first and second side as well as at least one opening, positioning a graphics appliquxc3xa9 with at least one translucent section adjacent to the first side of the light-carrying panel and aligning at least one, light source with the opening on the light-carrying panel. The light-carrying panel also has a first light-redirecting area on its first side and a second light-redirecting area on another side. Light is transmitted from the light source into the light-carrying panel through the opening and through the light-carrying panel to the second light-redirecting area and out through at least one translucent section of the graphics appliquxc3xa9.
In yet another embodiment, a method for providing illumination to an instrument panel is provided. The method includes the steps of providing a light-carrying panel with at least one opening defined in it for light to enter and at least one area defined in it for light to exit and at least one light source substantially aligned with the entrance opening. Light is directed into the entrance opening and into the light-carrying panel. The light is redirected out of the light-carrying panel through the exit area.